Effective block sparse representation algorithm for DOA estimation with unknown mutual coupling

Unknown mutual coupling effect can degrade the performance of a direction of arrival (DOA) estimation method. In this letter, a new method is proposed for uniform linear arrays (ULAs) to tackle this problem. Considering the sparse representation exploiting the inherent structure of the received data, the effective block sparse representation and the convex optimization problem is constructed using the steering vector parameterizing method. The proposed solution based on the l1- SVD (singular value decomposition) can exploit the information provided by the whole array and the Toeplitz structure of the mutual coupling matrix (MCM) in the ULA. Simulation results are provided to demonstrate its performance with unknown mutual coupling in comparison with some existing methods

Plant ABC Transporters

ABC transporters constitute one of the largest protein families found in all living organisms. ABC transporters are driven by ATP hydrolysis and can act as exporters as well as importers. The plant genome encodes for more than 100 ABC transporters, largely exceeding that of other organisms. In Arabidopsis, only 22 out of 130 have been functionally analyzed. They are localized in most membranes of a plant cell such as the plasma membrane, the tonoplast, chloroplasts, mitochondria and peroxisomes and fulfill a multitude of functions. Originally identified as transporters involved in detoxification processes, they have later been shown to be required for organ growth, plant nutrition, plant development, response to abiotic stresses, pathogen resistance and the interaction of the plant with its environment. To fulfill these roles they exhibit different substrate specifies by e.g. depositing surface lipids, accumulating phytate in seeds, and transporting the phytohormones auxin and abscisic acid. The aim of this review is to give an insight into the functions of plant ABC transporters and to show their importance for plant development and survival